1. Field of the Invention
The present invention relates to a thermostat device provided in a circulation channel, embeds a heat responding element which expands and shrinks by detecting the heating or cooling of a circulating liquid, slides a sliding member in accordance with a volume change resulting from the expansion and shrinkage of the heat responding element and opens and closes a valve having a valve shaft.
2. Description of the Related Art
In general, a thermostat device arranged in a cooling system of an internal-combustion engine and the like is configured that it provides a sensor case which embeds a heat responding element to expand and shrink by detecting a temperature change of a cooling liquid filled in a circulation channel of the cooling system, opens and closes a valve in accordance with a volume change resulting from the responding and shrinkage of the heat expansion element, and maintains the cooling liquid at a designated temperature.
FIG. 11 is a cutaway side elevational view of a circulation channel 4 which provides a thermostat device 50 having such configuration, as described in Japanese patent Laid-Open No. 7-301362. The thermostat device 50 in the figure has a pocket-type valve, and in more detail, it is consisted of a sensor case 51 which fills wax having a heat responding property, a piston guide 52 attached to a side of the sensor case 51, a piston rod 53 inserted into the piston guide 52 in a slidable manner, a diaphragm (not shown) inserted between the piston guide 52 and the sensor case 51, a valve body 54 fixed to the piston guide 52, and a coil spring 55 winding around the sensor case 51.
The thermostat device 50 having such configuration is positioned in the circulation channel 4 by being firmly fitted the tip end portion of the piston rod 53 into a fitting hole 57 bored in a flange portion 56 arranged in the circulation channel 4.
The thermostat device 50 arranged in the circulation channel 4 has following functions. When the temperature of a cooling liquid filled in the circulation channel 4 rises, the wax (not shown) filled in the sensor case 51 is expanded by heating, which pushes up the diaphragm to cause a deformation. By the deformation of the diaphragm, a semi-free flowing liquid (not shown) filled in the piston guide 52 is pressed toward the piston rod 53 to give the piston rod 53 a pushing force.
As described above, the tip end of the piston rod 53 is firmly fitted into the fitting hole 57 of the flange portion 56 formed in the circulation channel 4, so it pushes back the sensor case 51 against a resilient force of the coil spring 55, helped by responding of the heat expansion wax. Thus, the piston rod 53 moves the sensor case 51 downwards in the figure in accordance with the rise in temperature of the cooling liquid. Accompanied by the move, the valve body 54 moves to actuate an open-close portion 58 of the circulation channel 4 to open direction, making possible to allow the cooling liquid to pass in the direction shown by the arrow in the figure.
FIG. 12 is a cutaway side elevational view of the circulation channel 4 which provides another conventional thermostat device 50A. The thermostat device 50A shown in the figure provides, similar to the thermostat device 50 above described, a sensor case 51A which embeds a heat responding wax to expand or shrink by detecting the change in temperature of a cooling liquid filled in the circulation channel 4 in the cooling system, and has a function to keep the cooling liquid in a designated temperature by opening and closing a valve body 54A in accordance with the volume change resulting from the expansion or the shrinkage of the wax. But on the other hand, it is a different device from the previously described device in a respect of having another function that the device provides a heating element 59 in the sensor case 51A, the wax in the sensor case 51A is expanded by heating with the heating element 59, even when the cooling liquid filled in the circulation channel 4 is in low temperatures and the valve 54A is forcibly opened to make it possible to allow the cooling liquid to pass.
As explained above, the thermostat devices 50, 50A adopting the conventional poppet type valve bodies 54, 54A are both arranged with sensing portions such as sensor cases 51, 51A to detect temperature of the cooling liquid in the circulation channel 4 and slide portions of the piston rods 53, 53A to open and close the poppet type valve bodies 54, 54A. As the slidable piston rods 53, 53A, particularly, are always put in the cooling liquid, in some cases, the cooling liquid comes in between the piston rods 53, 53A and the piston guides 52, 52A resulting to harm the sliding function, or some ingredients may corrode these members to damage the functions.
Moreover, the cooling liquid in the circulation channel can not directly engage with the sensor case, disturbed by the poppet type valve bodies, that causes the temperature sensibility of the sensor case dull and the responsivity of the thermostat device poor.
When in such situation, a smooth flow of the cooling liquid in the circulation channel 4 can not be expected and at the same time, operation of the internal-combustion engine and the like may be seriously affected.
And as the thermostat devices 50, 50A are using the poppet type valve bodies 54, 54A which provide the sensing portion and the sliding portion in the circulation channel 4, flow resistance of the cooling liquid becomes big, and an increase of the diameter of the valve bodies 54, 54A is necessary to obtain a designated amount of flow. Then, size reduction of the thermostat devices 50, 50 themselves becomes difficult, accordingly, the miniaturization of a device such as the internal-combustion engine and the like can not be achieved.
As bleeding air to fill the cooling liquid in the circulation channel 4 is carried out by operating a jiggle valve (not shown) of the thermostat, the filling efficiency is quite poor. And in case that the valve bodies 54, 54A of the thermostat devices 50, 50A are in trouble, the circulation channel 4 can not be opened or closed from the outside.
Further more, for the thermostat device 50A which has a function to forcibly open the valve body 54A through heat expansion of the wax in the censor case 51A by the action of a heating element 59, the hermeticity of an electrode 59a of the heating element 59 and a shield wire 59b for conducting current must be strictly controlled because they are placed in the circulation channel 4. When an accident such as contact failure of the electrode 59a due to leakage of the cooling liquid or a break in the shield wire 59b is occurred, the function can not be performed and the replacement work requires much expense in time and effort.
In considering these disadvantages, the thermostat device of the present invention aims to provide a thermostat device that the sliding function is not impaired by immersion of the cooling liquid so that a good slidability is ensured, the design flexibility of the circulation channel can be improved through miniaturization, and an open-close operation of the valve can be manually performed.